[en] The IDQBRN/CTEx has a Cs-137 research irradiator to promote research development in the field of material irradiation, assisting in obtaining data and scientific publications in the area. Currently, tests are being conducted with pellets and plates of materials placed at the base of the irradiator chambers, requiring verification of the absorbed dose to water in the central areas of the chambers, where the plates and pellets are positioned, ensuring the dose delivered in processes, as well as ensuring a corresponding average value for each material positioned within this measured area. By using the Fricke chemical dosimeter, it was possible to determine that for the central position closest to the door of the upper chamber of the irradiator, the highest absorbed dose in water found in the measurements conducted was a value of 5.10% above the expected value compared to the last dosimetry performed with a ceric-cerous sulfate chemical dosimeter. The results show that using the Fricke dosimeter it was possible to characterize the irradiator obtaining complete dosimetry and doses according to the positioning of the material within the chamber to subsequently create a simulator that could be used for dosimetry of the irradiation volume. (author)

[en] The IDQBRN/CTEx has a Cs-137 research irradiator whose purpose is to promote the development of research in the area of irradiation of materials, assisting in the acquisition of data and scientific publications in the area. Because it is used for research, it is necessary to verify the distribution of dose point in the irradiator chambers. The purpose of this work is to carry out a five-point dosimetry of each irradiator chamber, using the Fricke chemical dosimeter. This dosimeter is used worldwide in several areas of medical and industrial physics, presenting relevant characteristics such as low cost, uncertainties of less than 3% in industrial applications, in addition to being an absolute and primary dosimeter. Dosimetry was performed in the IDQBRN/CTEx irradiator drawers where the materials to be irradiated are placed in the research irradiator chambers. (author)

[en] Metal dusting is a serious limitation on the lifetime of materials used in modern petrochemical plants which are moving to the use of higher carbon activity environments to improve plant efficiency. A 316 stainless steel alloy has been subjected to accelerated metal dusting in the laboratory using temperatures and pressure typical of plant using 25%CO-75%H₂ syngas at 450-650 deg. C and 40 bar. A precipitate and graphite based model for metal dusting in other environments has been evaluated in the newer more aggressive test conditions. Electron and X-ray diffraction have been used for the identification of the carbide and oxide precipitates. EELS TEM has been used for quantification of carbon levels. The orientation of graphite relative to austenite particles that survive intact into the coke has been examined using HRTEM